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You love them, you feed them, you welcome them into your homes and even your beds. But no matter how much you share with your dog, he can’t tell you why he just spent 20 minutes settling on a place to pee. And your cat is never going to attach a note to the dead mouse she just left on your doorstep. That’s why PARADE rounded up some experts (human ones!) to help clear up pet owners’ top head-scratchers.

1. Why do dogs drool (and why do some dogs drool more than others)? If your pup’s friendly welcome leaves your clothes looking like they’ve been attacked by a giant slug, you can probably thank his genes: Certain breeds’ lips just leak more than others. Notorious droolers like Newfoundlands, bloodhounds, and basset hounds have loose jowls and lots of skin around their mouths where saliva can accumulate, making it far too easy for them to share their slobber. As for the reasons for drooling, dogs are like humans: Their mouths release saliva in the presence of food, or when they’re anxious or excited. This behavior is perfectly normal, but if your dog begins to slobber more than usual, or if the saliva smells bad, you may want to swing by the vet: A wound in the mouth (from, say, a splinter), a dental infection, or even poisoning might be behind it.

2. Why do cats chase balls of string? Your cat’s obsession with yarn is not unlike a lion’s interest in a gazelle: Stalking string is a predatory behavior, a very watered-down and domesticated version of a hunt. “This type of play is good for cats; it helps discharge their prey-chasing instinct, and it also keeps them physically active and alleviates boredom,” says veterinarian Michael W. Fox, syndicated pet columnist and author of Cat Body, Cat Mind. But since string can damage a cat’s digestive system if swallowed, try substituting a laser pointer—many cats love to chase its light.

3. Why do dogs chase their tails? “Sometimes, it’s just a sign that the dog is craving interaction and playtime,” says Warren Eckstein, an animal behaviorist and therapist and host of the syndicated radio ­program The Pet Show. If that’s the case, you might put a stop to it by distracting your dog with another activity, like fetching a ball or tugging a rope. But if ­tail-chasing—or biting—­becomes a ritual (say, before going outside or getting fed), or if it becomes excessive (the dog works itself into a frenzy), it could signal an obsessive-compulsive disorder that requires help from an animal behaviorist or a vet.

4. Why do cats present their owners with “kills”? Experts agree that if your cat leaves a mouse on your doorstep, you should take it as a compliment. “It’s actually a very warm, friendly thing for a cat to do,” says Patricia McConnell, certified animal behaviorist and author of The Other End of the Leash. “It’s kind of like bringing flowers.” If the mouse is dead, it’s probably just a gift, similar to the kill a lion brings back to its pride. But if the animal is still breathing, your cat may also be mimicking a behavior she displays with her kittens: bringing half-dead ­animals home to teach her ­babies (or, in this case, you) how to finish the job.

5. Is it true that dogs are color-blind? Dogs do see color but, much like color-blind humans, they have difficulty distinguishing between certain hues. Humans have three types of cones (the cells in the eye that recognize ­color); dogs have only two. As a result, they see fewer colors than we do, and these colors are less rich. (Cats also have only two types of cones, and they see colors even less vividly than dogs.) “The common form of color blindness in people is red-green color blindness, and that’s really what dogs have, too,” says Jay Neitz, Ph.D., a professor of ophthalmology and a color vision researcher at the University of Washington in Seattle. For dogs, the rainbow is reduced to two colors, “blue at one end and yellow at the other, with colorless bands where pure red and pure green would be.” But don’t feel too sorry for your pup: What dogs lack in color-perceiving cones they make up for in an abundance of rods, the cells in the eye that aid night vision. They are also exceptionally good at spotting movement, which is why your dog is aware of every squirrel in your yard even when he’s got all four paws inside.

6. Why do dogs sniff around so much before deciding where to pee? “Before there was Facebook, there were telephone poles,” jokes ­Stephen Zawistowski, Ph.D., science adviser for the American Society for the Prevention of Cruelty to Animals. Canines’ highly acute sense of smell enables them to gather all sorts of information from the scents of other dogs’ urine, including which dogs passed by, how long ago they visited, even whether they were male or female. “It’s like a news feed; your dog is just taking his time to read everything that happened before he got there,” Zawistowski explains.

7. Why do cats hate getting wet? They don’t. Well, at least not all of them —some breeds of cats, like Turkish Vans, will actively seek out water. What they do hate are unplanned ­soakings: slipping into a pool or being squirted with a garden hose or disciplined with a spray bottle. If you have a kitten and want to teach him not to fear a bath, Eckstein recommends the following technique: Place the kitten in a dry sink on a nonskid mat for several minutes with some treats. Repeat this for a few days. Then slowly add a bit of water to the sink each day. “Eventually, your cat will come to associate water and bath time with rewards, rather than punishment,” says Eckstein.

8. Do pets have any sense of time? Animals, like humans, have internal body clocks that are sensitive to the time of day. They also can accurately measure intervals between events; if a rat receives a reward for sticking its head in a feeder one minute after hearing a tone, it will start poking its head in more frequently as the 60-second mark approaches. “The more controversial question is whether they have a sense of time that extends well into the past and into the future,” says Bill Roberts, Ph.D., professor emeritus of psychology at Western University in Ontario. For years, experts assumed that animals were stuck in the here and now, but Roberts, who studies animal cognition, says that recent research shows that pets may possess at least a limited mental timeline. In one of the most famous studies, researchers from the ­University of Cambridge and UC Davis allowed scrub jays to hide wax worms and peanuts in different locations and then ­permitted the birds to retrieve the treats either four hours or five days later. The birds prefer worms, so it was no surprise that after the four-hour delay, the jays sought them out before the peanuts. But worms don’t last as long as ­peanuts, and so after five days—at which point the worms were well past their expiration date—the jays sought out the peanuts before the worms. This suggested that the jays had a sense of when the food had been cached.

9. Why do dogs pant? (And what about cats?) Panting is a way for dogs to cool off. (It can also be a sign of excitement.) Both cats and dogs have sweat glands on the pads of their paws, but these aren’t enough to effectively cool their entire bodies. Panting, which brings quick gusts of air over dogs’ moist tongues, is much more effective. Overheated cats will pant, too —they’re just less likely to spend a scorching afternoon chasing squirrels.

10. Are onions and chocolate really poisonous to pets? Yes—but for different reasons, and to varying degrees, says veterinarian Ahna Brutlag, assistant director of veterinary services at the Pet Poison Helpline. Chocolate contains a chemical called theobromine, related to caffeine, that dogs and cats can’t metabolize as well as humans can. If they ingest too much of the chemical, the result is similar to what might happen if you took a handful of caffeine pills: agitation, pacing, and panting. In worst-case scenarios, it can lead to cardiac arrhythmias, seizures, or even death. The darker the chocolate, the more theobromine it contains and the more poisonous it will be just two to three ounces of baking chocolate can be toxic to a 50-pound dog. Theobromine is also toxic to cats, but for some reason maybe because they lack taste receptors for sweetness they tend to have less of an appetite for chocolate than dogs do. Onions, along with garlic, leeks, and chives, contain chemicals called propyl disulfides and thiosulfates, which damage pets’ red blood cells. It doesn’t matter whether the vegetables are fresh, frozen, cooked, or freeze-dried: In high enough doses, they can cause the walls of the red blood cells to weaken and break down; in the most serious cases, a blood transfusion is needed. Cats are more vulnerable to these chemicals than dogs; a little more than a tablespoon of raw onions will poison a 10-pound cat. The most telltale symptom is intense lethargy, which can begin anywhere from a day to three days after ingestion. (To learn more about what ­human foods are toxic to pets—like raisins and grapes for dogs —visit petpoisonhelpline.com.)

11. Why do cats purr? MA purring cat may be a stereotypical image of feline bliss, but the ­behavior doesn’t always indicate happiness. “I’ve seen badly injured cats, and as you gently lift them up, you can feel them purring,” says Zawistowski. While purring can signal contentment, it can also serve as a soothing ritual for the cat or its kittens (which is why cats sometimes purr while feeding their young).

12. Is there such a thing as a hypoallergenic pet? In a word, no. That’s because allergies aren’t triggered by fur, as is commonly believed, but by dander — a general term for protein materials, present in animals’ skin, urine, and saliva, that cause immune responses in people who are sensitive to them. A low-shed breed like the Obamas’ Portuguese water dog may leave less dander-covered fur lying around, but—no offense to Bo —it’s allergenic all the same. Still, some simple steps can reduce dander in your home. The most important one: Keep your pet out of your bedroom. “The animal should have its own sleeping space, with a mat that is washable,” says Angel Waldron, spokesperson for the Asthma and Allergy Foundation of America. She also suggests covering any ­ventilation grates in the pet’s room with a piece of cheese cloth or gauze. ­“Dander is so light that once it gets airborne, it can ­travel easily from room to room through your ventilation system.” Next, clean rugs and carpets weekly using an asthma- and allergy-friendly vacuum cleaner with a HEPA filter, and dust hard surfaces with special dander-trapping wipes or a damp cloth. Wash linens frequently in hot water (over 130 degrees) and avoid heavy curtains, which are magnets for ­allergens. “You’ll never entirely rid your house of dander,” says Waldron. “But at least you can minimize your exposure.”